Rallybio Receives Approval for Phase 2 Trial of RLYB212 in High-Risk Pregnant Women

Rallybio Corporation, a clinical-stage biotechnology firm, has received approval to commence its Phase 2 clinical trial for RLYB212, aimed at pregnant women at higher risk for HPA-1a alloimmunization and fetal and neonatal alloimmune thrombocytopenia (FNAIT). This approval has been granted by the European Medicines Agency (EMA) and the United Kingdom's Medicines and Healthcare products Regulatory Agency (MHRA).

Rallybio will activate clinical trial sites and start screening participants in the fourth quarter of 2024. Stephen Uden, M.D., Chief Executive Officer of Rallybio, highlighted the significance of these approvals, emphasizing the dedication and innovation of the team in progressing this groundbreaking program. The objective is to prevent maternal alloimmunization and FNAIT, conditions with potentially severe consequences.

The Phase 2 clinical trial, identified as 2024-512651-20/NCT06435845, will be conducted in Belgium, the Netherlands, Norway, Sweden, and the UK. It is designed to evaluate the pharmacokinetics (PK) and safety of RLYB212, a monoclonal anti-HPA-1a antibody, in eight pregnant women at higher risk for HPA-1a alloimmunization and FNAIT. The trial's secondary objectives include assessing pregnancy and neonatal/infant outcomes and the occurrence of emergent HPA-1a alloimmunization. Participants will receive subcutaneous administration of RLYB212 starting from Gestational Week 16 and continuing every four weeks through parturition.

Steven Ryder, M.D., Chief Medical Officer at Rallybio, expressed pride in the organization’s role in bringing innovative solutions to women's health, particularly in addressing FNAIT, an area long overlooked.

Fetal and Neonatal Alloimmune Thrombocytopenia (FNAIT) is a rare and potentially life-threatening condition that can lead to uncontrolled bleeding in fetuses and newborns. The disease occurs due to an immune incompatibility between a pregnant woman and her fetus concerning a specific platelet antigen called human platelet antigen 1 (HPA-1). Predominantly, there are two forms of HPA-1, known as HPA-1a and HPA-1b, which are expressed on platelet surfaces. Individuals who are homozygous for HPA-1b, possessing two copies of the HPA-1b allele and none of the HPA-1a allele, are known as HPA-1a negative. These individuals may develop antibodies to HPA-1a upon exposure, leading to alloimmunization.

In pregnant women who are HPA-1a negative carrying an HPA-1a positive fetus, alloimmunization can occur when fetal blood mixes with maternal blood. This results in the mother developing anti-HPA-1a antibodies that can cross the placenta and destroy fetal platelets, leading to thrombocytopenia. The consequences can be severe, including miscarriage, stillbirth, neonatal death, or severe lifelong neurological disabilities in surviving infants. Currently, no approved therapy exists for the prevention or prenatal treatment of FNAIT.

Rallybio is also engaged in other clinical programs, including RLYB116, an inhibitor of complement component 5 (C5), with potential applications in treating diseases related to complement dysregulation. The company, headquartered in New Haven, Connecticut, focuses on developing and commercializing therapies for patients with severe and rare diseases. Their efforts extend across maternal fetal health, hematology, and metabolic disorders, driven by a mission to address unmet medical needs.